For treating the wounds of cut surfaces on plants, especially trees, which come about as a result of cutting back or pollarding, pruning or thinning of budding or grafting, use has long been made of filler-comprising covering compositions which initially were formed essentially by natural materials, such as tar or tree wax, or--borrowed from the building sector--were based on mortarlike or paintlike compositions.
With the increasing development of synthetic resins, laminates and polymers, and also of active ingredients and pesticides, especially fungicides, more differentiated methods of plant treatment were developed.
For instance, as early as in DE-C 1 281 206, a composition for treating tissue-damaged plants was described which comprises an aqueous synthetic-resin dispersion which has cellulose as its filler, is intended for brush application and binds well to the plant.
DE-A 2 023 262 discloses a pesticidal pest control composition for forestry which is applied in mobile form and hardens in air to become viscous.
U.S. Pat. No. 4,456,587 provides a mixture which is intended for spray application to the leaves of the plants that are to be treated and which is based on polyvinyl alcohol/polyvinyl pyrrolidone in aqueous dispersion, in which an active ingredient (pheromone or insecticide), mixed with oil, is finely divided. The polymer mixture dries or "cures" on the plant and releases the active ingredient to the plant over a period of several weeks.
DE-A 35 07 008 emphasizes the positive effect of finely ground rock flour (&lt;4.mu.) in a spreadable plant treatment composition based on polymers, synthetic resins or natural resins.
DD 272 219 describes treating tree wounds by brushing them with two coats of paint, which involves first of all coating the bark of the tree with a latex binder and, after it has set, carrying out treatment with a composition which comprises active ingredient, alkyd resin and phyllosilicate.
DD 273 573 A1 reveals a pastelike composition for controlling bark-breeding pests, such as bark beetles, which is spread onto the bark and which in addition to the active ingredient(s) comprises terpene hydrocarbons, such as .alpha.-pinene, or myrcene, and is suitable for the controlled, delayed release of active ingredient(s). Covering with plastic film is recommended as a means of avoiding environmental contamination.
Again, more recently, DE Patent Application P 44 30 449.8 has proposed a sprayable preparation of active ingredient which results in a water-insoluble, pressure-sensitively adhering film with controlled, delayed release of active ingredient.
U.S. Pat. No. 5,395,851, finally, describes a sprayable or spreadable composition comprising a fungicide in a mixture of natural and synthetic resin and metal salts of fatty acids.
None of these diverse efforts appears to be entirely satisfactory: the coverings produced in feasible technology, with more or less good adhesiveness, have the disadvantage that there may be losses of active ingredient into the surroundings, especially as a result of the effects of weathering, and that there is an increased risk to free-living animals. Layer application by spray technology is not without its problems for the user, and layers having good adhesiveness can result in adjacent plant parts becoming stuck.
An additional covering with plastic film is to start with complex and ackward and, moreover, is not always possible when there are spatial constraints.